Combustion apparatus

ABSTRACT

There is provided a combustion apparatus for reducing generation of NOx by securing more time for mixing fuel and air and uniformly mixing fuel and air. 
     The combustion apparatus includes: a modifying part configured in the center to modify supplied hydrocarbon-based fuel and air and discharge high temperature modified gas including hydrogen to an outlet; and a supply part configured at an outer side of the outlet to jet fuel and air to one side of the modified gas discharged from the modifying part to form a flame at a position spaced apart by a pre-set distance from the outlet.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2012-0086479 filed in the Korean IntellectualProperty Office on Aug. 7, 2012, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a combustion apparatus for reducinggeneration of NOx by forming flame at a position distant from an outletby jetting a gas including high temperature hydrogen generated bymodifying hydrocarbon fuel.

(b) Description of the Related Art

A general combustion apparatus is configured to make supplied fuel andair meet in the interior or exterior to form a diffusion flame. Here, ageneration rate of NOx (or generation of NOx) may differ according to amixture degree and a mixture speed of fuel and air.

In order to reduce generation of NOx, a combustion apparatus for jettingair or fuel by multiple stages or performing fuel-rich combustion andlean combustion by several stages has been developed. However,multi-staged combustion lengthens flame and makes a structure of acombustion apparatus complicated.

In an effort to solve the problem, a combustion apparatus capable ofreducing generation of NOx by mixing fuel and air rapidly has beendeveloped. In this case, the combustion apparatus requires an ignitor(i.e., a lighter or a firer) for igniting flame, and a pilot flame forsettling and stabilizing in a combustion apparatus should be formed inan outlet of the combustion apparatus. Namely, without the pilot flame,flame is blown out from the outlet of the combustion apparatus.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide a combustionapparatus having advantages of reducing generation of NOx by securingmore time for mixing fuel and air and uniformly mixing fuel and air.

The present invention has also been made in an effort to provide acombustion apparatus having advantages of forming a flame at a positiondistant from an outlet, without being blown out, by modifying fuel andsupplying a modified gas including hydrogen from the center of theoutlet.

An exemplary embodiment of the present invention provides a combustionapparatus including: a modifying part configured in the center to modifysupplied hydrocarbon-based fuel and air and discharge high temperaturemodified gas including hydrogen to an outlet; and a supply partconfigured at an outer side of the outlet to jet fuel and air to oneside of the modified gas discharged from the modifying part to form aflame at a position spaced apart by a pre-set distance from the outlet.

An equivalence ratio of hydrocarbon-based fuel in the mixture of fueland air supplied to the modifying part may range from a stoichiometricratio of partial oxidation to a stoichiometric ratio of combustion.

The modifying part may include a first housing electrically earthed; andan electrode separately installed in the center within the first housingand receiving a voltage applied thereto.

The first housing may include: a discharge region forming a dischargegap with the electrode therebetween to allow fuel and air to react undera partial oxidation condition; and an expanded region expanded from thedischarge region to stabilize gas discharged after being reacted in thedischarge region.

The supply part may be formed to jet fuel and air to an outer side ofthe modified gas discharged from the modifying part.

The supply part may include a second housing separately disposed on anouter circumference of the first housing and a third housing separatelydisposed on an outer circumference of the second housing, and mayfurther include a fuel passage formed between the first housing and thesecond housing and an air passage formed between the second housing andthe third housing.

The air passage may be connected to the discharge region across the fuelpassage by a passage connection member connecting the second housing andthe first housing.

The second housing may have a side wall formed at one side of the fuelpassage, and the first housing may be connected to the side wall througha method such as screw-connection, welding, or the like.

The first housing may further include a coupling portion protrudedtoward the side wall of the second housing, the fuel passage may includean inflow side formed at the center of one side of the first housing anda supply side connected to the outer circumference of the first housing,and the coupling portion may include a through hole connecting theinflow side and the supply side.

An end portion of the first housing includes a flange formed to beprotruded to an outer side in a diameter direction of the second housingsuch that a space is formed with an end portion of the second housing ina length direction of the second housing in the opposite side of theside wall of the second housing, and the space set between the flangeand the end portion of the second housing may allow the supply side ofthe fuel passage to open to the outside in the diameter direction of thesecond housing.

The end portion of the second housing and an end portion of the thirdhousing may be disposed in the same line in the diameter direction.

The first housing may include an inner member forming an air nozzlejetting air toward the electrode, and an outer member coupled to anouter circumference of the inner member and accommodating air to bejetted through the air nozzle upon receiving it.

A plurality of air nozzles may be disposed to be spaced apart from eachother in a circumferential direction in the inner member, and may havean angle sloped with respect to a diameter direction of the innermember.

The supply part may be formed to jet fuel and air in a directionparallel to the direction in which the modified gas is discharged froman outer side of the modified gas discharged from the modifying part.

The supply part may include a second housing separately disposed on anouter circumference of the first housing and a third housing separatelydisposed on an outer circumference of the second housing, and mayfurther include a fuel passage formed between the first housing and thesecond housing and an air passage formed between the second housing andthe third housing, and an end portion of the first housing may include aflange disposed at an inner side of an end portion of the second housingand protruded inwardly in a diameter direction of the first housing.

The end portion of the first housing and the end portion of the secondhousing may be formed to be parallel to each other, and a first swirlermay be installed between the end portion of the first housing and theend portion of the second housing and a second swirler may be installedbetween the end portion of the second housing and the end portion of thethird housing.

According to embodiments of the present invention, the modifying partmodifies fuel to discharge a modified gas including hydrogen andsupplies fuel and air to an outer side of an outlet to the supply part,and thus, a flame can be stably formed at a position spaced apart by apre-set distance from the outlet.

Thus, a time for mixing fuel supplied from the supply part and air canbe further secured by a time corresponding to the distance between theoutlet of the combustion apparatus and the flame. Since the mixture timeis lengthened, fuel and air can be more uniformly mixed, and thus,generation of NOx can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional perspective view of a combustion apparatusaccording to a first embodiment of the present invention.

FIG. 2 is a sectional view of the combustion apparatus illustrated inFIG. 1.

FIG. 3 is a sectional view taken along line III-Iii in FIG. 2.

FIG. 4 is a photograph showing a state of a flame when fuel is burnt bythe combustion apparatus of FIG. 1.

FIG. 5 is a photograph showing a state of a flame when fuel is burnt bythe related art combustion apparatus.

FIG. 6 is a sectional view of a combustion apparatus according to asecond embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, the present invention will be described more fullyhereinafter with reference to the accompanying drawings, in whichexemplary embodiments of the invention are shown. As those skilled inthe art would realize, the described embodiments may be modified invarious different ways, all without departing from the spirit or scopeof the present invention. The drawings and description are to beregarded as illustrative in nature and not restrictive. Like referencenumerals designate like elements throughout the specification.

FIG. 1 is a partial sectional perspective view of a combustion apparatusaccording to a first embodiment of the present invention. FIG. 2 is asectional view of the combustion apparatus illustrated in FIG. 1. FIG. 3is a sectional view taken along line III-Iii in FIG. 2.

Referring to FIGS. 1 to 3, a combustion apparatus 1 according to a firstembodiment of the present invention includes a modifying part 100 formodifying hydrocarbon-based fuel into a high temperature modified gasincluding hydrogen and a supply part 200 jetting fuel and air to anoutlet 101 of the combustion apparatus 1. Hydrogen included in themodified gas has fast combustion speed and fast diffusion speed. Thus,the high temperature modified gas and hydrogen supplied from themodifying part 100 form a flame F at a position distant from the outlet101 of the combustion apparatus 1 and prevents the flame F from beingblown off. Namely, the modified gas and hydrogen may stabilize the flameF at a position distant from the outlet 101 of the combustion apparatus1.

To this end, the modifying part 100 is provided in the center of thecombustion apparatus 1 and configured to make supplied fuel reactaccording to a partial oxidation condition to modify it into a gasincluding high temperature hydrogen and discharge the hydrogen and themodified gas to the outlet 101.

The modified gas discharged from the modifying part 100 is jetted to afront side (the flame F) from the outlet 101 to push the flame F basedon the combustion of the fuel supplied from the supply part 200 and airto stably maintain the flame F at a position distant from the outlet 101by a pre-set distance L.

In the present embodiment, the modifying part 100 is integrally providedin the combustion apparatus 1, so it can stably supply hydrogen towardthe air and fuel supplied from the supply part 200 to the outlet 101.Thus, the modifying part 100 can supply hydrogen by a simpleconfiguration, and thus, namely, an additional device for supplyinghydrogen is not required.

The supply part 200 is provided at an outer side of the outlet 101 andconfigured to jet fuel and air to an outer side of the dischargedmodified gas to form the flame F. The supply part 200 according to thepresent embodiment is formed to have a structure for accommodating themodifying part 100. The fuel and air supplied from the supply part 200is pushed by a pre-set distance L from the outlet 101 by the modifiedgas supplied from the modifying part 100.

However, due to fast combustion and spreading speed of the hightemperature modified gas and hydrogen supplied from the modifying part100, the fuel and air supplied from the supply part 200 are burnt at aposition distant from the outlet 101 by the distance L, rather thanbeing blown off, thus stably maintaining the flame F.

The distance L set between the outlet 101 and the flame F secures alonger period of time for mixing fuel and air supplied from the supplypart 200. Thus, the fuel and air in a state of having left the outlet101 may be further uniformly mixed while proceeding by the distance L.

In this manner, the combustion apparatus 1 according to the presentembodiment can drastically generation of NOx by using the fastcombustion and spreading performance of the high temperature modifiedgas and hydrogen generated in the modifying part 100 when fuel is burnt.

When a mixture ratio of the fuel and air in the modifying part 100 isexcessively rich, a partial oxidation reaction does not take place andhydrogen is not generated. Conversely, when the mixture ratio of thefuel and air in the modifying part 100 is overly close to a combustionratio, the flame is maintained only within the modifying part 100 andhydrogen is not generated.

When hydrogen is not generated in the modifying part 100, flame formedaccording to combustion of fuel and air supplied to the supply part 200is blown out in the outlet 101 of the combustion apparatus 1. Thus, amixture of fuel and air is required to have an appropriate equivalenceratio.

For example, since a stoichiometric ratio of partial oxidation in ahydrocarbon-based fuel is 0.5 and a stoichiometric ratio of combustionis 2.0. Thus, in case of LNG having methane as a main ingredient in amixture of fuel and air in the modifying part 100, O₂/C ratio may rangefrom 0.7 to 1.9.

The combustion apparatus 1 will be described in detail. The modifyingpart 100 includes a first housing 10 supplying air and electricallyearthed, and an electrode E separately installed at the center withinthe housing 10 to supply fuel and receiving a voltage HV appliedthereto.

When the voltage HV is applied to the electrode E, plasma dischargeoccurs in the fuel and air mixed between the electrode E and the firsthousing 10. In this case, the fuel is partially oxidized to form a hightemperature modified gaseous state including hydrogen.

The first housing 10 includes a discharge region 111 and an expandedregion 112 set according to a direction in which a gas modified as fueland air are introduced is discharged. The discharge region 111 has adischarge gap G formed between the first housing 10 and the electrode E,and plasma discharge occurs in the discharge gap G to allow suppliedfuel and air to react under a partial oxidation condition so as to bemodified.

The expanded region 112 is formed to be expanded greater than a diameterof the discharge region 111 at one side of the discharge region 111, andstabilizes gas discharged after being reacted under the partialoxidation condition and discharges the stabilized gas. Namely, themodified gas reacted under the partial oxidation condition isre-circulated in the large space of the expanded region 112 so as to bestabilized.

The supply part 200 includes a second housing 20 separately disposed onan outer circumference of the first housing 10 and a third housing 30separately disposed on an outer circumference of the second housing 20.In this case, the first housing 10 is accommodated in the secondhousing, and the second housing 20 is accommodated in the third housing30 by stages. For example, the first, second, and third housings 10, 20,and 30 may form a concentric circular structure.

A fuel passage P1 is formed between the first housing 10 and the secondhousing 20, and an air passage P2 is formed between the second housing20 and the third housing 30. The fuel passage P1 and the air passage P2supply fuel and air supplied to one side thereof to the modifying part100 and the supply part 200.

For example, the air passage P2 is connected to the discharge region 111of the modifying part 100 across the fuel passage P1 by a passageconnection member 22 connected to the first housing 10 by passingthrough the second housing 20. The air passage P2 supplies air to thedischarge region 111. Also, the air passage P2 supplies air between endportions E2 and E3 of the second and third housings 20 and 30 of thesupply part 200.

For example, the second housing 20 includes a side wall 21 formed at oneside of the fuel passage P1, and the first housing 10 may be connectedto the side wall 21 of the second housing 20 through various methodssuch as screw connection, welding, or the like. For the screwconnection, the first housing 10 further includes a coupling portion 11protruded toward the side wall 21 of the second housing 20. Namely, amale screw of the coupling portion 11 is screw-connected to a femalescrew of the side wall 21.

Here, the fuel passage P1 set between the first and second housings 10and 20 includes an inflow side P11 formed in the center at one side ofthe first housing 10 and a supply side P12 connected to an outercircumference of the first housing 10.

The coupling portion 11 of the first housing 10 includes a through hole12 connecting the inflow side P11 and the supply side P12 of the fuelpassage P1. As soon as air introduced to the inflow side P11 is suppliedto the discharge region 111, it is supplied to the supply side P12through the through hole 12 of the coupling portion 11.

In the opposite side of the side wall 21 of the second housing 20, thefirst housing 10, the first housing 10 includes a flange 13 formed on anend portion E1 set in one side of the second housing 20 in a lengthdirection (in a horizontal direction in FIG. 2).

The flange 13 is formed to be protruded to the outside in a diameterdirection of the second housing 20 and forms a space C with the endportion E2 of the second housing 20. The space C allow the supply sideP12 of the fuel passage P1 to be open toward the outer side in adiameter direction of the second housing 20, so that supplied fuel canbe supplied toward the outer side of the second housing 20.

Here, the end portion E2 of the second housing 20 and the end portion E3of the third housing 30 are disposed in the same straight line in thediameter direction, allowing air supplied through the air passage P2 tobe mixed with fuel supplied between the both end portions E2 and E3.

Namely, fuel supplied through the fuel passage P1 is supplied to the endof the air passage P2 through the space C so as to be mixed with airsupplied through the air passage P2, and discharged to a front side ofthe outlet 101 in the combustion apparatus 1 to form the flame F.

The size of the space C may be adjusted according to a range in whichthe coupling portion 11 of the first housing 10 is fastened to the sidewall 21 of the second housing 20. A mixture ratio of air and fuel may beset by controlling supply of fuel through the fuel passage P1 withrespect to supply of air through the air passage P2 according to a sizeof the space C.

Also, the first housing 10 includes an inner member 14 and an outermember 15 coupled to partially overlap with each other in a lengthdirection. The inner member 14 includes an air nozzle 16 jetting airtoward the electrode E of the discharge region 111.

A plurality of air nozzles 16 are disposed to be spaced apart from theinner member 14 in a circumferential direction, and have an angle (θ)sloped with respect to a diameter direction of the inner member 14 (SeeFIG. 3). Thus, air supplied to the air nozzle 16 is supplied while beingrotated in the circumferential direction between the electrode E and thefirst housing 10 and in the gap G.

The outer member 15 includes a chamber 17 coupled to an outercircumference of the inner member 14 and accommodating air uponreceiving it from the air nozzle 16. Thus, the chamber 17 makes amountsof air jet through the plurality of air nozzles 16 uniform by uniformlymaintaining pressure of supplied air.

Meanwhile, the electrode E forming the discharge region 111 togetherwith the inner member 14 includes a fuel nozzle 26 jetting fuel. Thefuel nozzle 26 is connected to the inflow side P11 of the fuel passageP1 and jets supplied fuel to the inner wall of the inner member 14 inthe vicinity of the gap G.

The fuel jetted to the gap G of the discharge region 111 is mixed withair rotated upon being jetted through the air nozzle 16, and reactsunder a partial oxidation condition, while generating a rotating arc bya voltage HV set between the electrode E and the inner member 14.Namely, fuel is modified into a high temperature gas including hydrogen.

The hydrogen and the modified gas modified in the discharge region 111is recirculated in the expanded region 112 so as to be stabilized anddischarged to the outlet 101. The discharged hydrogen and modified gasact as pushing force in the distance L within a pre-set range in frontof the outlet 101 to thrust fuel and air supplied to the supply part 200out of the range of the distance L.

Thus, the fuel and air supplied to the supply part 200 reaches outsideof the range of the distance L through the outside of the region of thehydrogen and modified gas. At the same time, the modified gas ismaintained to have a high temperature state and hydrogen has a fastcombustion and spreading speed. Thus, the fuel and air supplied to thesupply part 200 is implemented for lean combustion outside of the rangeof the distance L, stably maintaining the flame F.

While proceeding by the distance L, the fuel and air supplied to thesupply part 20 are mixed to have a further uniform state for anadditional mixture time, implementing lean combustion. Thus, when fuelis burnt, generation of NOx can be reduced.

FIG. 4 is a photograph showing a state of a flame when fuel is burnt bythe combustion apparatus 1 of FIG. 1, and FIG. 5 is a photograph showinga state of a flame when fuel is burnt by the related art combustionapparatus.

Referring to FIGS. 4 and 5, the related art combustion apparatus 2approaches the outlet to form a flame F2. In comparison, the combustionapparatus 1 according to an embodiment of the present inventionstabilizes the flame F at a position distant from the outlet 101 by thedistance L. It can be seen that the flame F is not formed in the centralportion of the outlet 101.

Hereinafter, a second embodiment of the present invention will bedescribed. A description of the same configuration as that of the firstembodiment will be omitted and a different configuration from that ofthe first embodiment will be described.

FIG. 6 is a sectional view of a combustion apparatus according to asecond embodiment of the present invention. Referring to FIG. 6, in acombustion apparatus 3 according to the second embodiment of the presentinvention, a supply part 300 is formed to jet fuel and air in adirection parallel to the discharge direction of the modified gas at anouter side of the modified gas including hydrogen discharged from themodifying part 100.

For example, an end portion E21 of the first housing 10 includes aflange 23 disposed at an inner side of an end portion E22 of the secondhosing 20 and protruded inwardly in a diameter direction of the firsthousing 10.

The flange 23 is formed to narrow the outlet 102 in the discharge region111 to thus lower or adjust a speed of the modified gas includinghydrogen sprut through the outlet 102.

An end portion E23 of the third housing 30 is disposed to be parallel inthe outlet 102 together with the end portion E22 of the second housing20. A first swirler S1 may is provided between the end portions E21 andE22 of the first and second housings 10 and 20 forming the fuel passageP1 in order to swirl discharged fuel. A second swirler S2 is providedbetween the end portions E22 and E23 of the second and third housings 20and 30 forming the air passage P2 in order to swirl discharged air.

Thus, fuel discharged between the end portions E21 and E22 of the firstand second housings 10 and 20 and air discharged between the endportions E22 and E23 of the second and third housings 20 and 30 areswirled to be mixed by the first and second swirlers S1 and S2, so as tobe discharged while being swirled in a direction parallel to thedischarge direction of the modified gas.

The fuel and air mixed by the first and second swirlers S1 and S2 mayform the flame F, without being blown out, at a position distant fromthe outlet 102 by the distance L according to the discharge speed of themodified gas.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

<Description of symbols>  10, 20, 30: first, second, and third housing 11: coupling portion  12: through hole  13, 23: flange  14: innermember  15: outer member  16: air nozzle  17: chamber  21: side wall100: modifying part 101, 102: outlet 111: discharge region 112: expandedregion 200: supply part C: interval E1, E2, E3, E21, E22, E23: endportion F: flame L: distance P1: fuel passage P11: inflow side P12:supply side P2: air passage  1, 2, 3: combustion apparatus

What is claimed is:
 1. A combustion apparatus comprising: a modifyingpart configured in the center to modify supplied hydrocarbon-based fueland air and discharge high temperature modified gas including hydrogento an outlet; and a supply part configured at an outer side of theoutlet to jet fuel and air to one side of the modified gas dischargedfrom the modifying part to form a flame at a position spaced apart by apre-set distance from the outlet.
 2. The combustion apparatus of claim1, wherein an equivalence ratio of hydrocarbon-based fuel in the mixtureof fuel and air supplied to the modifying part ranges from astoichiometric ratio of partial oxidation to a stoichiometric ratio ofcombustion.
 3. The combustion apparatus of claim 1, wherein themodifying part comprises: a first housing electrically earthed; and anelectrode separately installed in the center within the first housingand receiving a voltage applied thereto.
 4. The combustion apparatus ofclaim 3, wherein the first housing comprises: a discharge region forminga discharge gap with the electrode therebetween to allow fuel and air toreact under a partial oxidation condition; and an expanded regionexpanded from the discharge region to stabilize gas discharged afterbeing reacted in the discharge region.
 5. The combustion apparatus ofclaim 3, wherein the supply part is formed to jet fuel and air to anouter side of the modified gas discharged from the modifying part. 6.The combustion apparatus of claim 5, wherein the supply part comprises asecond housing separately disposed on an outer circumference of thefirst housing; and a third housing separately disposed on an outercircumference of the second housing, and further comprises: a fuelpassage formed between the first housing and the second housing; and anair passage formed between the second housing and the third housing. 7.The combustion apparatus of claim 6, wherein the air passage isconnected to the discharge region across the fuel passage by a passageconnection member connecting the second housing and the first housing.8. The combustion apparatus of claim 6, wherein the second housing has aside wall formed at one side of the fuel passage, and the first housingis connected to the side wall through a method such as screw-connectionor welding.
 9. The combustion apparatus of claim 8, wherein the firsthousing further comprises a coupling portion protruded toward the sidewall of the second housing, the fuel passage comprises an inflow sideformed at the center of one side of the first housing and a supply sideconnected to the outer circumference of the first housing, and thecoupling portion comprises a through hole connecting the inflow side andthe supply side.
 10. The combustion apparatus of claim 9, wherein an endportion of the first housing includes a flange formed to be protruded toan outer side in a diameter direction of the second housing such that aspace is formed with an end portion of the second housing in a lengthdirection of the second housing in the opposite side of the side wall ofthe second housing, and the space set between the flange and the endportion of the second housing allows the supply side of the fuel passageto open to the outside in the diameter direction of the second housing.11. The combustion apparatus of claim 10, wherein the end portion of thesecond housing and an end portion of the third housing are disposed inthe same line in the diameter direction.
 12. The combustion apparatus ofclaim 3, wherein the first housing comprises: an inner member forming anair nozzle jetting air toward the electrode; and an outer member coupledto an outer circumference of the inner member and accommodating air tobe jetted through the air nozzle upon receiving it.
 13. The combustionapparatus of claim 12, wherein a plurality of air nozzles are disposedto be spaced apart from each other in a circumferential direction in theinner member, and have an angle sloped with respect to a diameterdirection of the inner member.
 14. The combustion apparatus of claim 3,wherein the supply part is formed to jet fuel and air in a directionparallel to the direction in which the modified gas is discharged froman outer side of the modified gas discharged from the modifying part.15. The combustion apparatus of claim 12, wherein the supply partcomprises: a second housing separately disposed on an outercircumference of the first housing and a third housing separatelydisposed on an outer circumference of the second housing, and furthercomprises: a fuel passage formed between the first housing and thesecond housing and an air passage formed between the second housing andthe third housing, and an end portion of the first housing includes aflange disposed at an inner side of an end portion of the second housingand protruded inwardly in a diameter direction of the first housing. 16.The combustion apparatus of claim 15, wherein the end portion of thefirst housing and the end portion of the second housing are formed to beparallel to each other, and a first swirler is installed between the endportion of the first housing and the end portion of the second housingand a second swirler is installed between the end portion of the secondhousing and the end portion of the third housing.